execute payment paypal flutter

I am trying to implement paypal payments in a WebApp, but WebView is not compatible with the web.i also tried dart: ui but without success.

//ignore: undefined_prefixed_name  ui.platformViewRegistry.registerViewFactory('paypal-html',      (int viewId) => IFrameElement()        ..width = MediaQuery.of(context).size.width.toString()        ..height = MediaQuery.of(context).size.height.toString()        ..src = checkoutUrl        ..style.border = 'none');SizedBox(          width: MediaQuery.of(context).size.width,          height: MediaQuery.of(context).size.height,          child: HtmlElementView(viewType: 'paypal-html'),        ),

Do you know how I can do it?